[haydenukhayden]

I have been chasing this issue on my 2011 F11 520d m sport for over a year.The problem occurs when I apply very light brake pressure at around 80mph which sends vibrations through the pedal (back of the car) and ultimately the entire car the vibration doesn't occur when I apply medium to firm pressure. Trying to Solve this problem the car has had new alloys new tyres new discs pads 3d laser align and the disc straightened using an on car lathe twice. Any ideas? As its costing me a small fortune

[IanS100]

Bushes?

[MrPogle]

It seems odd that a problem which occurs under light braking could be wheels or tyre related but I'm no expert. I'm also surprised that having fitted new discs they need straightening with a lathe. Assuming you don't do stupid things like drive along with your foot resting on the brake or sit at lights with your foot on the brake after very heavy braking, it could feasibly be that the car is activating the brakes in error whilst you are just driving along and they are overheating. Go for a normal drive for 20 mins without braking hard and then see if your discs are hot.

[haydenukhayden]

Bushes and driveshaft is what the mechanic is said he would try next to the tune of an eyewatering £2400. With the comment of 'it might fix it' i got a second garage to look at it with more or less the same prognosis.The theory about an on car lathe is that no wheel hub turns absolutely balanced so although the disc will be perfectly straight when fitted the wheel hub isn't, thus causing the vibrations. All the bushes have been checked with no signs of wear. Brake disc don't get hot. One thing that I have noticed which might be some clue is after the disc have been on the lathe it seems to amplify the problem and then it gets better after a few hundred miles. Its really driving me mad and both mechanics have been left umming and arring guessing what the fault maybe :/

[CraigUK]

What discs have you purchased, OEM or aftermarket? I purchased several sets of Pagid front discs for my last car (E91) and had exactly the same issue. They were fine initially but then after a few weeks developed the same symptoms you describe.

In the end I sold the car before resolving but the consensus on the E90 forum was that Pagid discs aren't as good as they could be.

[IanS100]

Check the mating surfaces under the disc, if they're dirty or rusty and the brake disc isn't sitting exactly flat / level as it should, that would feel a lot like warped discs

[haydenukhayden]

I have fitted Zimmermann disc and pads. The problem was apparent with the OEM discs to . The mating surfaces between the disc and hub is immaculate. Even if there was dirt between the disc and hub the on car lathe would cancel that out in theory. Think I might need a third opinion from another BMW specialist :/. Thanks for your opinions so far, keep then coming maybe there is something i haven't covered yet

[MrPogle]

For a 2400 bill on a 5 year old car, it's got to be a consideration to sell it and use the 2400 as a cost to change, surely?

[warmshed]

It may well be the pad/discs. They can glaze. I would try a new se of pads first

[HighlandPete]

Originally Posted by haydenukhayden

I have been chasing this issue on my 2011 F11 520d m sport for over a year.The problem occurs when I apply very light brake pressure at around 80mph which sends vibrations through the pedal (back of the car) and ultimately the entire car the vibration doesn't occur when I apply medium to firm pressure. Trying to Solve this problem the car has had new alloys new tyres new discs pads 3d laser align and the disc straightened using an on car lathe twice. Any ideas? As its costing me a small fortune

My first question is, did this condition build up gradually, or suddenly appear?

Second, did any of the above work/replacements actually change the condition, even temporarily?

[haydenukhayden]

I am seriously considering selling it but apart from this issue I really like the car.I have had two sets of pads and disc on the cars so I really don't think that is the issue anymore. During all this the only noticeable change is when I straightened the rear disc it made the problem worse for the first 1500miles then it was back to normal.

[HighlandPete]

Originally Posted by haydenukhayden

I am seriously considering selling it but apart from this issue I really like the car.I have had two sets of pads and disc on the cars so I really don't think that is the issue anymore. During all this the only noticeable change is when I straightened the rear disc it made the problem worse for the first 1500miles then it was back to normal.

From how you describe the problem and the attempts to solve, I'm minded it is a drivetrain issue on very light 'braked' overrun. Do you sense 'any' vibration if you go lightly on and off the throttle at the same sort of speed as you get the light braking issue?

BTW, I'd expect rear brake vibration to have a wider spread than just light braking, often gets worse as you load the brakes.

[haydenukhayden]

I'm inclined to agree with you on the drivetrain. I have the car booked in for a third opinion at the end of the week. The vibration only occurs under light braking tried throttling on and off and nothing is felt at all Are you thinking driveshafts or flexiable coupling forward. The thing is upon inspection non of these parts have any loose or look worn.

[HighlandPete]

Originally Posted by haydenukhayden

I'm inclined to agree with you on the drivetrain. I have the car booked in for a third opinion at the end of the week. The vibration only occurs under light braking tried throttling on and off and nothing is felt at all Are you thinking driveshafts or flexiable coupling forward. The thing is upon inspection non of these parts have any loose or look worn.

Difficult to guess what is going on. My thinking, if it did a similar thing on the throttle I'd suspect it could be in the prop shaft (first call) or drive shaft(s), but as it is induced by the braking action, it is more likely to be close to them, as the loading through the suspension on the overrun, is different to to braking.

Are the drive shafts being checked both hanging and in a normal ride height position? Don't assume suspension bushes are all tight, again how they test them can be the difference in showing a bit of wear. Also check wheel hub bearings, not all worn bearings get noisy at first, needs a careful investigation before you start throwing more money at parts.

[haydenukhayden]

Driveshafts and bushes tested with weight on the wheels with a crowbar. None shown any movement. Bearings have no lateral play at all.
Up until today i was convinced that the issue was drivetrain related To confuse matters further today I tried a different test which seems a bit obvious now but my car being an auto I didn't think of doing.let's assume that it is the driveshafts that have play in them, meaning when the brake is applied on overrun the resistance from the engine brake is causing the shaft to vibrate due to the torque that is being applied by the brakes. So today I placed the car in neutral at the speed when the vibration occurs with the theory that the lesser resistance from the engine would either stop or significantly reduce the vibration. The vibration is exactly the same. I know that the driveshaft is still rotating at the same speed but surely if it was drivetrains related having it in neutral would have changed the characteristics of the vibration at a minimum.

This thing has started driving me mad hehe hope what I just wrote makes sense

[HighlandPete]

Originally Posted by haydenukhayden

...So today I placed the car in neutral at the speed when the vibration occurs with the theory that the lesser resistance from the engine would either stop or significantly reduce the vibration. The vibration is exactly the same. I know that the driveshaft is still rotating at the same speed but surely if it was drivetrains related having it in neutral would have changed the characteristics of the vibration at a minimum.

This thing has started driving me mad hehe hope what I just wrote makes sense

Interesting, as I was going to suggest you try the neutral test. I'd also expect it to be different.

Your earlier comment on the 'lathed' discs being worse to start with, is a bit puzzling, does hint at it being associated with the braking. Not a calliper issue is it? I assume they've been checked for ease of movement when pads were changed. A worn suspension bush is still a possibility, but do suspect a rotating part.

[haydenukhayden]

The car spent all yesterday in the 3rd garage I am -£100 down and no closer to resolving the issue. I was also thinking caliper but they have been cleaned up and the pads slide easily its hard to test if they are applying a constant pressure and not pulsating which I doubt cause I would imagine I would have the vibration at all speeds or maybe it can't be felt at lower speed. Again it would be a punt as nothing is obvious. I'm going to bite the bullet and take it BMW main dealer.I will be wearing short shorts as I assume it will just make it quicker!!!!

[spirocheter]

This is what I was about to suggest a few posts back, taking it to a main dealer. I hope you don't come away with a voice a few octaves higher.

I don't know whether you saw the other thread about brake disc choices? I had posted my experience with an e90 335d I still own, where the Pagid discs and pads warped, despite gentle-ish driving. They weren't out by very much. It was gradual. We were actually in Germany driving on autobahns at pretty high speeds, but without any particularly heavy braking, when the problem first manifested, about 3k miles after initially fitting the new discs / pads.

These were changed to Honeywell / Bosch disc and pad combo and the problem soon became apparent again, not nearly as severely. The car was driven very conservatively to allow the pads and discs to bed in. I had a local, well respected mechanic check all manner of things, not certain it was the brakes. They were not showing up as being out by very much.

I now have Bosch discs and Bosch pads and although less severe, the problem of juddering, which is quite faint, is still present from high speeds. I don't like the fact the car is not perfect, but I don't think it'll be causing bushing wear etc as it really is quite mild.

I am toying with the idea still, of fitting genuine BMW pads and discs, so everything on the car will be genuine. I had thought of taking the car to the main dealer, but I am afraid their response (after a very good specialist has already checked all manner of things, providing a second opinion) will be to replace to BMW genuine discs and pads.

I had actually come out of the rolling extended monthly warranty as I had been quoted by the dealer in the first place, what I thought was an extortionate amount. The amount of aggravation and cost, has exceeded what it would have cost to have stuck with the main dealer in the first place, plus they would have taken the hit to investigate. Lesson learnt for me.

Please do post back, as I'm very interested to hear the resolution. The best of luck.

[silo24]

Very similar issue with my 535d.

Warranty replaced pads/discs front twice, rear once and it still came back.

I have also replaced the runflats with normal tyres which actually seemed to reduce the sensation but it still became noticeable.

When I complained the third time they replaced some front suspension components due to excessive play in the bushings which seems to have done the trick.

I think the 'feel through pedal=rear' is misleading on this chassis, especially with RFT's.

[haydenukhayden]

Booked in at the main stealers at the end of the month to coincide with payday.in the meantime I have been clocked doing 102mph tying to figure out this vibration issue just received court summons today and now trying to figure out how to explain to the judge that I was trying to figure out if my vibration issue had been resolved or not. #notmyluckymonth

[ChrizLoud]

I know the thread is old but did you solve this?
I have exactly the same problem. New Ate discs and pads. Rear is still vibrating under light braking.

[haydenukhayden]

Nope I had new discs put on again and it would be ok for a while then it comes back again. Now what I do is rotate the discs 90° on the hub when i have the wheel off which cures the problem for a few months then it comes back again . I have been given a billion theories what it could be and bar changing absolutely everything at once ie caliper ,hub disc,pad and brake lines I have no other suggestion. Frankly I gave up with it and just live with it.in addition to the above I have recently changed all the control arms and rotated the discs which seems to have cured the problem completely (for bow) only time will tell !!!! So it may have been play in the lower control arm ? Good luck is all I can say